Ancona Help I have 4 ancona chicks ordered all Female but i think one is a Male!

[ItalianoChicken]

One started stretching neck and roosting alot I thought male behavior but still thought well i dont know. Now that chick has a larger crown than the rest the same age and a thicker crest and its darker yellow in color? Am I crazy? or is this a rooster? and How do i know!
Thanks ItalianoChicken

 

[ChickenLover200]

Do you have a picture?